Derived Types and Allocatable

Allocatable Array

Runtime Size

An allocatable array gets its size at run time with allocate, and is released with deallocate.

Program

Play the program to allocate three slots, fill them, and total them.

allocatable_array.f90 
program allocatable_array_demo
    implicit none
    integer, allocatable :: nums(:)
    integer :: i
    allocate(nums(3))
    do i = 1, 3
        nums(i) = i * 10
    end do
    print '(I0)', sum(nums)
    deallocate(nums)
end program allocatable_array_demo
allocatable `integer, allocatable :: nums(:)` declares without a size.
allocate `allocate(nums(3))` reserves storage at run time.
deallocate `deallocate` releases the storage.